1 /*-
2 * Copyright (c) 2001-2007, by Cisco Systems, Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are met:
6 *
7 * a) Redistributions of source code must retain the above copyright notice,
8 * this list of conditions and the following disclaimer.
9 *
10 * b) Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the distribution.
13 *
14 * c) Neither the name of Cisco Systems, Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived
16 * from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
20 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
22 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
28 * THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 /* $KAME: sctp_crc32.c,v 1.12 2005/03/06 16:04:17 itojun Exp $ */
32
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD: releng/8.1/sys/netinet/sctp_crc32.c 206181 2010-04-05 13:48:23Z rrs $");
36
37 #include <netinet/sctp_os.h>
38 #include <netinet/sctp.h>
39 #include <netinet/sctp_crc32.h>
40 #include <netinet/sctp_pcb.h>
41
42
43 #if !defined(SCTP_WITH_NO_CSUM)
44
45 static uint32_t
46 sctp_finalize_crc32c(uint32_t crc32c)
47 {
48 uint32_t result;
49
50 #if BYTE_ORDER == BIG_ENDIAN
51 uint8_t byte0, byte1, byte2, byte3;
52
53 #endif
54 /* Complement the result */
55 result = ~crc32c;
56 #if BYTE_ORDER == BIG_ENDIAN
57 /*
58 * For BIG-ENDIAN.. aka Motorola byte order the result is in
59 * little-endian form. So we must manually swap the bytes. Then we
60 * can call htonl() which does nothing...
61 */
62 byte0 = result & 0x000000ff;
63 byte1 = (result >> 8) & 0x000000ff;
64 byte2 = (result >> 16) & 0x000000ff;
65 byte3 = (result >> 24) & 0x000000ff;
66 crc32c = ((byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3);
67 #else
68 /*
69 * For INTEL platforms the result comes out in network order. No
70 * htonl is required or the swap above. So we optimize out both the
71 * htonl and the manual swap above.
72 */
73 crc32c = result;
74 #endif
75 return (crc32c);
76 }
77
78 uint32_t
79 sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
80 {
81 /*
82 * given a mbuf chain with a packetheader offset by 'offset'
83 * pointing at a sctphdr (with csum set to 0) go through the chain
84 * of SCTP_BUF_NEXT()'s and calculate the SCTP checksum. This also
85 * has a side bonus as it will calculate the total length of the
86 * mbuf chain. Note: if offset is greater than the total mbuf
87 * length, checksum=1, pktlen=0 is returned (ie. no real error code)
88 */
89 uint32_t base = 0xffffffff;
90 struct mbuf *at;
91
92 at = m;
93 /* find the correct mbuf and offset into mbuf */
94 while ((at != NULL) && (offset > (uint32_t) SCTP_BUF_LEN(at))) {
95 offset -= SCTP_BUF_LEN(at); /* update remaining offset
96 * left */
97 at = SCTP_BUF_NEXT(at);
98 }
99 while (at != NULL) {
100 if ((SCTP_BUF_LEN(at) - offset) > 0) {
101 base = calculate_crc32c(base,
102 (unsigned char *)(SCTP_BUF_AT(at, offset)),
103 (unsigned int)(SCTP_BUF_LEN(at) - offset));
104 }
105 if (offset) {
106 /* we only offset once into the first mbuf */
107 if (offset < (uint32_t) SCTP_BUF_LEN(at))
108 offset = 0;
109 else
110 offset -= SCTP_BUF_LEN(at);
111 }
112 at = SCTP_BUF_NEXT(at);
113 }
114 base = sctp_finalize_crc32c(base);
115 return (base);
116 }
117
118 #else
119
120 uint32_t
121 sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
122 {
123 return (0);
124 }
125
126 #endif /* !defined(SCTP_WITH_NO_CSUM) */
127
128
129 void
130 sctp_delayed_cksum(struct mbuf *m, uint32_t offset)
131 {
132 struct ip *ip;
133 uint32_t checksum;
134
135 ip = mtod(m, struct ip *);
136 checksum = sctp_calculate_cksum(m, offset);
137 SCTP_STAT_DECR(sctps_sendhwcrc);
138 SCTP_STAT_INCR(sctps_sendswcrc);
139 offset += offsetof(struct sctphdr, checksum);
140
141 if (offset + sizeof(uint32_t) > (uint32_t) (m->m_len)) {
142 printf("delayed m_pullup, m->len: %d off: %d p: %d\n",
143 (uint32_t) m->m_len, offset, ip->ip_p);
144 /*
145 * XXX this shouldn't happen, but if it does, the correct
146 * behavior may be to insert the checksum in the appropriate
147 * next mbuf in the chain.
148 */
149 return;
150 }
151 *(uint32_t *) (m->m_data + offset) = checksum;
152 }
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